title: Lung volumes and emphysema in smokers with interstitial lung abnormalities.
abstract: BACKGROUND
  Cigarette smoking is associated with emphysema and radiographic interstitial lung abnormalities. The degree to which interstitial lung abnormalities are associated with reduced total lung capacity and the extent of emphysema is not known.
  
  
  METHODS
  We looked for interstitial lung abnormalities in 2416 (96%) of 2508 high-resolution computed tomographic (HRCT) scans of the lung obtained from a cohort of smokers. We used linear and logistic regression to evaluate the associations between interstitial lung abnormalities and HRCT measurements of total lung capacity and emphysema.
  
  
  RESULTS
  Interstitial lung abnormalities were present in 194 (8%) of the 2416 HRCT scans evaluated. In statistical models adjusting for relevant covariates, interstitial lung abnormalities were associated with reduced total lung capacity (-0.444 liters; 95% confidence interval [CI], -0.596 to -0.292; P<0.001) and a lower percentage of emphysema defined by lung-attenuation thresholds of -950 Hounsfield units (-3%; 95% CI, -4 to -2; P<0.001) and -910 Hounsfield units (-10%; 95% CI, -12 to -8; P<0.001). As compared with participants without interstitial lung abnormalities, those with abnormalities were more likely to have a restrictive lung deficit (total lung capacity <80% of the predicted value; odds ratio, 2.3; 95% CI, 1.4 to 3.7; P<0.001) and were less likely to meet the diagnostic criteria for chronic obstructive pulmonary disease (COPD) (odds ratio, 0.53; 95% CI, 0.37 to 0.76; P<0.001). The effect of interstitial lung abnormalities on total lung capacity and emphysema was dependent on COPD status (P<0.02 for the interactions). Interstitial lung abnormalities were positively associated with both greater exposure to tobacco smoke and current smoking.
  
  
  CONCLUSIONS
  In smokers, interstitial lung abnormalities--which were present on about 1 of every 12 HRCT scans--were associated with reduced total lung capacity and a lesser amount of emphysema. (Funded by the National Institutes of Health and the Parker B. Francis Foundation; ClinicalTrials.gov number, NCT00608764.).
authors.affiliation: Pulmonary and Critical Care Division, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
authors.forename: George R
authors.initials: GR
authors.lastname: Washko
authors.forename: Gary M
authors.initials: GM
authors.lastname: Hunninghake
authors.forename: Isis E
authors.initials: IE
authors.lastname: Fernandez
authors.forename: Mizuki
authors.initials: M
authors.lastname: Nishino
authors.forename: Yuka
authors.initials: Y
authors.lastname: Okajima
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Yamashiro
authors.forename: James C
authors.initials: JC
authors.lastname: Ross
authors.forename: Raúl San José
authors.initials: RS
authors.lastname: Estépar
authors.forename: David A
authors.initials: DA
authors.lastname: Lynch
authors.forename: John M
authors.initials: JM
authors.lastname: Brehm
authors.forename: Katherine P
authors.initials: KP
authors.lastname: Andriole
authors.forename: Alejandro A
authors.initials: AA
authors.lastname: Diaz
authors.forename: Ramin
authors.initials: R
authors.lastname: Khorasani
authors.forename: Katherine
authors.initials: K
authors.lastname: D'Aco
authors.forename: Frank C
authors.initials: FC
authors.lastname: Sciurba
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Silverman
authors.forename: Hiroto
authors.initials: H
authors.lastname: Hatabu
authors.forename: Ivan O
authors.initials: IO
authors.lastname: Rosas
mesh_terms: D015331:Cohort Studies; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology*; D017563:Lung Diseases, Interstitial / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology*; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology*; D011658:Pulmonary Fibrosis / Q000000981:diagnostic imaging / Q000473:pathology; D012907:Smoking / Q000009:adverse effects / Q000473:pathology*; D013147:Spirometry; D014057:Tomography, X-Ray Computed / Q000379:methods; D014109:Total Lung Capacity